chemical physics of discharges - Argonne National Laboratory

FUFARCI! INSTITUTE OF TFYDLC UNIVERSTTY
b150 KNRY P.VE.
V'TIJDFLPPJA, PA.
INTRODIJCTICN
uses,
Dlasma penerators, in general, have been found suitable for a variety of
Thev penerally Drovide an electric arc which is condensed or constricted
into a smaller circular cross-section than would ordinarily exist in an onen arc-tyDe
device. This constriction penerates a very hinh temperature (8,000-20,000°K) so
that a sunerheated-Dlasna workinp fluid can he ejected throuph the nozzle and the
comoosition of the Dlasma determine the use to which the plasma nenerator is put.
Plasma Fenerators have been used for cuttinn, welding, metal spravine and chemical
orocessinr. For chemical processinp, plasma penerators have provided the possibility
of the production of new aaloys and compounds and the processing of less commonly
used materials, as well as the preoaration of certain common chemicals.
nLAS#A JET EQUTPMrNT
Two types of plasma generators are possible: the nontransferred and the
transferred arc. A nontransferred arc consists of a cathode and a hollow anode
where the arc is struck between the electrodes and the flame emerges through the
orifice in the anode, In the transferred arc, the cathode is placed some distance
away from the anode and an arc is passed between the electrodes. The nontransferred
arc is the nost popular in the'chemical studies made to date.
A plasma jet used in chemical synthesis can have varied desips to meet 1
special requirements, such as
oath at a particular point.
the introduction of a reactant material into the flame
Consumable cathodes have been used in experiments in which carbon was one of \
the reactants, Carbon, vaporized from a graphite cathode, was used in the synthesis
of cyanogen and hydrogen cyanide. powdered carbon introduced in a gas stream or as a
constituent of a Kas has also been used as the source of carbon in a plasma flame.
Electrodes of 2%-thoriated tungsten are the most frequently used water-cooled
nonconsumable electrodes, Hater-cooled copper anodes have been widely used in experhens
work. Figure 1 shows a typical plasma jet assembly. A reactor chamber may be of my
confipuration desired to accomodate different feedinp: and quenching devices.
PLASMA tTET REACTIONS
GAS-CAS PEACTIONS TO PRODUCE A CAS AND CAS
DFCO?'POS7TION PEACTIONS TO PFODUCF A GAS
A considerable amount of research has been done by a number of people in
the area of Dlasma jet eas-pas reactions.
pases that have been investipated.
The followinp is the gas reaction producing
I
\
\
i
x
\'
x
\
I
t
\'